In prior art light valve devices of the kind noted above, the light modulator panels (e.g. formed of PLZT materials) have been fabricated to have a series of selectively addressable electrode pairs that are spaced along a linear direction to form an array of discrete light modulator pixel portions. When a particular electrode pair is addressed to form an electric field across the intervening panel portion, the light, which is polarized in a first direction is shifted in polarization direction by that panel portion. A second output polarizer (analyzer) that is oriented 90.degree. to the input polarization direction, will therefore pass light, so modulated by field activated panel portions, and block light that is not so modulated. To obtain maximum modulation effect (and therefore good contrast) for such light valves, it is desirable that the direction of the modulator field be normal to the input light beam and at 45.degree. to the input light polarization direction. The downstream polarizer (i.e. analyzer) is oriented at 90.degree. to the input light polarization direction.
Electrodes have been fabricated on such modulator panels as surface configurations (see U.S. Pat. No. 4,406,521) and as in depth configurations (see U.S. Pat. No. 4,707,081 and the prior art teachings described therein). The in depth electrode approach is generally preferred because it enables a uniform electric field to be effective, in a normal direction to the passing light beam, throughout a large portion of the light passage distance through the modulator panel thickness another fabrication method, to achieve in depth electrode modulator panels, is described in U.S. patent application Ser. No. 107,230 filed Oct. 9, 1987.
U.S. Pat. No. 4,765,721 discloses a light valve array construction which is less subject to stress induced light leakage This patent teaches that it is desirable to align the array direction of a light valve device so that the linear direction of its array of modulator elements is parallel and perpendicular, respectively, to the polarization directions of the sandwiching polarizers. This substantially reduces stress induced light leakage through the array element, which can be caused by thermal or mechanical stress of the modulator panel. The electric field of the '721 patent device is provided at 45.degree. to the direction of input light polarization by forming electrodes pairs on the surface of the modulator panel at 45.degree. to the linear direction of the array. The improvements obtained by the '721 patent approach are quite advantageous, and it would be desirable to attain its advantages in an in depth electrode construction. However, we have found that if electrodes are disposed on a 45.degree. centerline across the width of the ridge in an in ,depth electrode configuration, the resulting electric field is not uniformly operative at 45.degree. to the length of the ridge, and, more specifically, not uniformly at 45.degree. to the input light polarization direction.